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1994 E320,2003 S430
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Discussion Starter #1
Hi all, I have a 94 E320 with 193k miles. For the past few months i have noticed the car is consuming a lot of gas(about 13-15 mpg hwy). I used to get about 19-21 city and 25-29 hwy. I dont drive it hard either. I have always used 93 grade gas either Mobil or shell here in ohio. I changed air filter, oil and filter,fuel filter, spark plugs/wires at 190k. Engine harness upper/lower changed. Recently changed the whole exhaust, headers back since it was badly rusted and was getting loud. Any ideas, suggestions. Thanks in advance!
 

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2008 E350 4M, 2016 Audi Allroad, 2019 Audi Q5
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Start by pulling the codes and see if there is anything.
 

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1994 E320,2003 S430
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63 Posts
Discussion Starter #3
Ok, so i checked for codes and the only code that pops up is "Upshift Dealy Faulty". The transmission seems to shift normal. Could this be the reason its consuming a lot of gas. I tried to look for any leaks but didn't find any.
 

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For the past few months i have noticed the car is consuming a lot of gas(about 13-15 mpg hwy). I used to get about 19-21 city and 25-29 hwy.
Has the O2 sensor, or whatever it's called on these cars, original? These are classic worn out oxygen sensor symptoms.

If it's OEM, then yours lasted much longer than most. Don't freak out when you find out what they cost. They're about $100 each, and MB uses two.

The worst part is usually removing the old one. Long-term heat cycling = near welded threads.

edit: the upshift delay being 'broken', IMO, is actually a good thing. It doesn't hurt anything but emissions when cold.
 

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1994 E320,2003 S430
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63 Posts
Discussion Starter #5
Thanks for the help guys!! Good to know Upshift delay being bad is not a big deal.
 

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Thanks for the help guys!! Good to know Upshift delay being bad is not a big deal.
The upshift delay being broken will trigger a check engine light every X number of starts. It's 120 engine starts, or something like that.

Fortunately, resetting said light takes about 60 seconds after you've done it a few times.

Oh, and not to rub salt into the wound, but filling up, yesterday, I calculated 26.3 MPG, mostly highway commute, gasoline M104.

This is the highest MPG car I've owned! Most well-built is a significant bonus, too!
 
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